1, imitation diamond +GIA diamond certificate
Methods: The certificate was made from natural diamonds and pasted on imitation diamonds (cubic zirconia, synthetic moissanite, zircon, kyanite, etc.). ) Sell imitation diamonds as natural diamonds.
Some imitation diamonds are similar to diamonds in appearance, such as cubic zirconia, which is often displayed on the counter by jewelers.
2. Low quality diamond+high grade GIA diamond certificate
Methods: GIA certificate is inlaid with natural diamonds, but the color, clarity and cut grade of diamonds are different from those on GIA certificate.
Usually, low-grade natural diamonds are used to apply for high-grade natural diamond certificates, for example, the differential cutting becomes better, and the color and clarity grades are better than the actual ones.
If you buy an inferior diamond at the price of a high-grade diamond, you may lose about 50% of your property.
1, check the gia Diamond.
Almost every GIA diamond has a GIA number engraved on its waist, which is the GIA certificate number. You can check whether the number on the diamond waist is consistent with the number on the GIA certificate (the number on the diamond waist suggests buying a magnifying glass 10-20 times). If the numbers are incorrect or inconsistent, it is basically a set of certificates.
2, observe the diamond waist size
The coding font of GIA diamond waist is clear and standard, which can be easily observed with a magnifying glass of 10 or 20 times. The waist code is in the form of three "GIA" letters+numbers (currently GIA certificate numbers are all 10 digits), in which the three letters of "GIA" are double-line hollow-out fonts, followed by single-line font numbers.
This special laser engraving technology is difficult, difficult to forge and costly. So some fake laser codes are different from real GIA codes, which are easy to distinguish, such as the following figure:
The left side of the above picture shows GIA's conventional diamond waist size, and the right side shows forging. It can be seen that the "GIA" on the left is hollow, and the cold laser lettering technology makes its font clear, regular and looks very fine; The forged waist code on the right is carved by thermal laser, so the carved font color is very black (because the diamond itself is carbon, it turns black when burned by thermal laser), and the font enlargement is also very rough.
Note: This method can't completely confirm whether the diamond is certified or not, and further inspection is needed.
3. Check the diamond clarity flaw map.
If it is a gia certificate, you can use a magnifying glass to observe whether the defect position of the diamond is consistent with that described in the GIA certificate. If the types and locations of defects are consistent, it can almost be concluded that there is no problem; If there is a big difference, it is basically a set of certificates, which can be further re-examined.
This method has limitations. Diamonds with high clarity levels have few clarity characteristics, which are dIFficult to observe, such as VVS 1, if, FL and VVS2. It is better to observe the clarity levels of VS, SI and i. ..
4, check the diamond cutting ratio data.
Diamonds are all cut manually, and the cut ratio data is difficult to control, so it is almost impossible to find two diamonds with exactly the same cut ratio data.
By personally measuring the specifications of diamonds: table width ratio, crown angle, pavilion depth ratio, waist thickness ratio, etc. Compared with the measured data on the certificate, the error is less than 65438 0%, which is basically safe. If there is a big difference between the actual measured value and the cutting ratio data on the certificate, further testing is needed.
If you want to avoid buying a set of diamonds, you can try to ask the merchant to have two certificates, a GIA certificate and a national inspection certificate, and the grade information of the two certificates should match.
It is best to choose a formal and reliable merchant, such as a jewelry company that has been established for a long time. These businesses have been tested and have a high degree of credibility.
After buying diamonds, you can go to the local authoritative quality inspection department for re-inspection and contact the merchants in time if you have any questions.